Real-time oscilloscope for generating a fast real-time eye diagram

Patent metadata

Field	Value
Publication number	US-9442136-B2
Application number	US-201314016129-A
Country	US
Kind code	B2
Filing date	Sep 1, 2013
Priority date	Sep 1, 2013
Publication date	Sep 13, 2016
Grant date	Sep 13, 2016

Abstract

Disclosed is an improved real-time oscilloscope (“IRTO”) for generating a fast worst-case real-time eye diagram from an input signal. The IRTO may include signal conditioning circuitry, a digitizer, an acquisition memory, a clock and data recovery (“CDR”) module, a worst-case real-time eye diagram rendering (“WRTER”) module, and a display.

First claim

What is claimed is:

1. An improved real-time oscilloscope (“IRTO”) for generating a fast worst-case real-time eye diagram from an input signal, the IRTO comprising:
signal conditioning circuitry, wherein the signal conditioning circuitry is configured to receive the input signal and, in response, produce an adjusted input signal;
a digitizer in signal communication with the signal conditioning circuitry, wherein the digitizer is configured to receive the adjusted input signal and, in response, produce a digitized waveform;
an acquisition memory in signal communication with the digitizer, wherein the acquisition memory is configured to receive and store the digitized waveform received from the digitizer;
a clock and data recovery (“CDR”) module in signal communication with the acquisition memory, wherein the CDR module is configured to
detect a plurality of transitions in the digitized waveform,
determine a plurality of first threshold crossings and a plurality of second threshold crossings, wherein each first threshold crossing and each second threshold crossing corresponds to a transition of the plurality of transitions,
determine a plurality of waveform segments of the digitized waveform, wherein each waveform segment corresponds to a transition of the plurality of transitions, and
recover a plurality of recovered clocks from the digitized waveform, wherein each recovered clock of the plurality of clocks corresponds to a transition of the plurality of transitions;

a worst-case real-time eye diagram rendering (“WRTER”) module in signal communication with CDR module, wherein the WRTER module is configured to
determine a plurality of first time difference values from the plurality of first threshold crossings and the plurality of recovered clocks, wherein each first time difference value corresponds to a first time difference between a first threshold crossing, of a transition of the plurality of transitions, and a recovered clock corresponding to that transition,
determine a plurality of second time difference values from the plurality of second threshold crossings and the plurality of recovered clocks, wherein each second time difference value corresponds to a second time difference between a second threshold crossing, of a transition of the plurality of transitions, and a recovered clock corresponding to that transition,
determine a first worst-case time difference value from the plurality of first time difference values, wherein the first worst-case time difference corresponds to a first worst-case waveform segment of the plurality of waveform segments,
determine a second worst-case time difference value from the plurality of second time difference values, wherein the second worst-case time difference corresponds to a second worst-case waveform segment of the plurality of waveform segments; and
a display configured to display an overlay of the first worst-case waveform segment and second worst-case waveform segment, from the plurality of waveform segments, to form the fast worst-case real-time eye diagram.

2. The IRTO of claim 1 ,
wherein the CDR module is configured to further determine a plurality of third threshold crossings, wherein each third threshold crossing corresponds to a transition in the plurality of transitions, and
wherein each first threshold crossing occurs at a first threshold voltage, each second threshold crossing occurs at a second threshold voltage, and each third threshold crossing occurs at a third threshold voltage, and
wherein the third threshold voltage is greater than the second threshold voltage and less than the first threshold voltage value.

3. The IRTO of claim 2 , wherein the digitized waveform has an voltage amplitude range, wherein the first threshold voltage is equal to eighty percent of the voltage amplitude range, wherein the second threshold voltage is equal to twenty percent of the voltage amplitude range, and wherein the third threshold voltage is equal to fifty percent of the voltage amplitude range.

4. The IRTO of claim 2 ,
wherein the WRTER module is configured to further
determine a plurality of third time difference values from the plurality of third threshold crossings and the plurality of recovered clocks, wherein each third time difference value corresponds to a third time difference between a third threshold crossing, of a transition of the plurality of transitions, and a recovered clock corresponding to that transition,
determine a third worst-case time difference value from the plurality of third time difference values, wherein the third worst-case time difference corresponds to a third worst-case waveform segment of the plurality of waveform segments, and

wherein the display is configured to display an overlay of the first worst-case waveform segment, second worst-case waveform segment, and a third worst-case waveform segment from the plurality of waveform segments, to form the fast worst-case real-time eye diagram.

5. The IRTO of claim 4 ,
wherein the CDR module is configured to
determine a plurality of rising edge transitions and plurality of failing edge transitions, where each transition in the plurality of transitions is a rising edge transition or a failing edge transition, wherein each first threshold crossing, second threshold crossing, and third threshold crossing corresponds to a rising edge transition in the plurality of rising edge transitions, and
determine a plurality of fourth threshold crossings, plurality of fifth threshold crossings, and plurality of sixth threshold crossings, wherein each fourth threshold crossing, fifth threshold crossing, and sixth threshold crossing corresponds to a failing edge transition of the plurality of failing edge transitions, and

wherein each fourth threshold crossing occurs at the first threshold voltage, each fifth threshold crossing occurs at the second threshold voltage, and each sixth threshold crossing occurs at the third threshold voltage.

6. The IRTO of claim 5 ,
wherein the WRTER is configured to
determine a plurality of fourth time difference values from the plurality of fourth threshold crossings, wherein each fourth time difference value corresponds to a fourth time difference between a fourth threshold crossing, of a failing edge transition of the plurality of transitions, and a recovered clock corresponding to that failing edge transition,
determine a plurality of fifth time difference values from the plurality of fifth threshold crossings and the plurality of recovered clocks, wherein each fifth time difference value corresponds to a fifth time difference between a fifth threshold crossing, of a failing edge transition of the plurality of transitions, and a recovered clock corresponding to that failing edge transition,
determine a plurality of sixth time difference values from the plurality of sixth threshold crossings and the plurality of recovered clocks, wherein each sixth time difference value corresponds to a sixth time difference between a sixth threshold crossing, of a failing edge transition of the plurality of transitions, and a recovered clock corresponding to that failing edge transition,
determine a fourth worst-case time difference value from the plurality of fourth time difference values, wherein the fourth worst-case time difference corresponds to a fourth worst-case waveform segment of the plurality of waveform segments,
determine a fifth worst-case time difference value from the plurality of fifth time difference values, wherein the fifth worst-case time difference corresponds to a fifth worst-case waveform segment of the plurality of waveform segments,
determine a sixth worst-case time difference value from the plurality of sixth time difference values, wherein the sixth worst-case time difference corresponds to a sixth worst-ca

Assignees

• Keysight Technologies Inc

Inventors

• Duff Christopher P

Classifications

• G01R13/0254 Primary

  for triggering, synchronisation · CPC title

• G01R31/3171

  BER [Bit Error Rate] test · CPC title

• G01R13/0236

  for presentation of more than one variable · CPC title